Vaneaxial fan



Jan. 18, 1966 M. l. L EvY 3,229,896

VANEAXIAL FAN Filed Nov. 5, 1965 5 sheets-sheet 1 FIG. l

FIG. 4

INVENTOR. MARION I. LEVY A TTORNE YJ Jan. 18, 1966 M. l. LEVY 3,229,896

VANEAXIAL FAN Filed Nov. 5, 1963 3 Sheets-Sheet 2 INVENTOR. MARION l LEVY ATTORNEYS.

Jan. 18, 1966 M. LEVY 3,229,896

VANEAXIAL FAN Filed Nov. 5, 1965 5 Sheets-Sheet 5 INVEN TOR.

MARION I. LEVY FIG. 6

BY/MQ/j- A TTORNE Y'.

United States Patent O 3,229,896 VANEAXIAL FAN Marion I. Levy, Cleveland, Ohio, assignor to The American Agile Co., 'a corporation of Ohio Filed Nov. 5, 1963, Ser. No. 321,537 13 Claims. (Cl. 230-117) This invention relates to air moving devices, especially those used in connection with contaminated atmospheres, and more particularly relates to a cooling arrangement for a motor driven fan whereby the motor is cooled with air that is free of contamination.

Motor driven fans are, of course, well known and are Widely used for cooling, ventillating and a variety of other purposes. However, problems arise when motor driven fans are used to propel contaminated air which may be damaging to the fan motor. Contaminated air is herein used to refer to any air that may be damaging or dangerous when used in conjunction with a motor driven fan and may include abnormally hot, corrosive, or highly flamable or explosive gaseous mixtures.

The simplest and most direct solution to the problem is to provide a completely enclosed motor directly in the contaminated air path With no external ventillation and hence no access for the contaminated air to the interior of the motor. This arrangement, however, suffers yfrom the disadvantage that the exterior of the motor is still subject to any corrosive action that might be caused by the contaminated air tlowing about it. Furthermore, completely enclosed motors attain a high temperature which make them unsuitable for use in conjunction with relatively low temperature material such as corrosion resistant low-cost plastic. Furthermore, the totally enclosed motor is, of

' necessity, considerably larger than the conventional motor,

resulting in blockage of the air stream and thereby lowering the eiciency of the fan.

A second solution heretofore proposed has been to mount the motor externally of the contaminated air flow and to drive the fan indirectly by pulleys or belts. This arrangement has the disadvantage of requiring extra bearings, belts, and pulleys, as well as the probem of mounting the motor on the unit.

A more commonly used system employing a direct drive connection between a standard motor and the fan involves mounting the motor in a transverse duct, which duct is open to the atmosphere at each end so that the air stream from the fan must flow over and around the duct. In this construction the transverse duct is smaller than and at right angles to the main fan housing. A disadvantage of this construction is that the transverse duct offers considerable resistance to the flow of air. Furthermore, the transverse duct precludes the use of proper straightening vanes so that the fan cannot develop the high pressure characteristics available through a properly designed vaneaxial fan. An aditional disadvantage to the transverse duct system is that the motor is still subjected to any contaminants which may have leaked out into the ambient air since the transverse duct in which the motor is located is opened yat each end tothe surrounding atmosphere.

The present invention avoids the above-mentioned diiiiculties by providing a simplified direct-drive motor driven fan arrangement wherein the motor is provided with a separate source of cooling air maintained at a positive pressure. This makes possible the elimination of extra bearings, belt and pulleys, and greatly simplies the method of mounting the motor while at the same time reducing weight and structural complications. It makes possible the use of low cost corrosion resistant plastics further reducing the weight and ycost of the unit. Furthermore, the substantially uninterrupted periphery of the fan chamber permits the use of eicient guide vanes between the fan Patented Jan. 18, 1966 ICC enclosure and the motor housing to convert the rotational efrect of air from the fan into usable pressure thus providing a relatively high volume fan capable of producing maintained air flow at relatively high pressures such as often result in its use with duct work and other ventillating devices.

It is, therefore, one object of the present invention to provide a novel air-moving device.

Another object of the present invention is to provide a novel motor-driven fan.

Another object of the present invention is to provide a motor driven fan particularly suited for moving contaminated atmospheres.

Another object of the present invention is to provide a direct drive vaneaxial fan.

Another object of the invention is to provide a novel cooling system for electric motors.

These and further objects and advantages of the invention will be more apparent upon reference to the following specification, claims and appended drawings wherein:

FIGURE l is a perspective view with parts in section showing the novel vaneaxial fan of this invention.

FIGURE 2 is a vertical longitudinal section through the fan of FIGURE l.

FIGURE 3 is a cross section taken along line 3 3 of FIGURE 2.

FIGURE 4 is a plan view of one of the vanes of FIG- URE 3;

FIGURE 5 is a cross section showing a slightly modified construction, and

FIGURE 6 shows the fan of the present invention installed in a duct system.

Referring to the several iigures of the drawings, the vaneaxial fan of this invention generally indicated at 10 comprises a tubular fan housing 12 having end anges 14 and 16 provided with a plurality of Iannularly spaced apertures 18 and 20 for attachment to the duct work in which the fan is to be employed. Positioned coaxially within the -an housing 12 is a tubular motor housing 22 completely enclosing an electric drive motor 24. Motor housing 22 comprises an annular casing 26 closed oli at its front end by an end plate 28 and at its rear end by an end cap 30.

Motor 24 is provided with a drive shaft 32 to which is secured a fan wheel 34. Drive shaft 32 passes through a suitable seal 36 in end plate 28 which seals the interior of the motor housing 22 from the contaminated air in the yfan housing 12. Mounted on the front of the fan wheel 34 is a hub cover 38 and secured to the periphery of the wheel are a plurality of fan blades such as 40.

Motor 24 is also provided with a rearwardly extending drive shaft 42 which constitutes lan extension of the drive shaft 32 and which acts to drive a blower wheel 44. An annular barrier plate 46 is secured to the Casing 26 and is provided with a large central aperture 48 adjacent the inlet side of the blower wheel 44. Aperture 48 communicates with the interior of the end cap 30 which latter is provided with an aperture 50 communicating with an air inlet pipe 52 passing outwardly of the unit through the wall of the fan housing 12.

Motor housing 22 is supported within the fan housing 12 by a plurality of vanes 54 angularly spaced around the periphery of the fan housing as best seen in FIGURE 3. A-s shown in FIGURE 4, each vane S4 comprises an axially extending body portion 56 and a bent over leading edge or tip 58 bent outwardly from the plane of the body portion 56 by an angle of approximately 35. Motor 24 is in turn supported -at one end within motor housing 22 by four annularly spaced L-shaped lbrackets 60 attached to the casing 26 by carriage bolts 62. The heads of the bolts projecting externally of the motor housing 22 are preferably coated with polyethylene or other suitable anti-corrosive material. The opposite ends of the brackets 60 are suitably connected to a rectangular mounting plate 64 a-ttached to a rubber ring 65 which, as a part of the motor, surrounds the motor anti-friction bearing 66 rotatably receiving the blower wheel drive shaft 42. Plate '64 is attached to rubber ring65 by `a plurality of binding screws'67. A similar mounting plate 68 is connected by carriage bolts such as 70 to end plate 28 and similarly is attached by a rubber ring to the motor `ball bearing 72 rotatably receiving the drive shaft 32. The

`outer ends'of the carriage bolts 70 projecting externally of the motor housing 22 are similarly preferably coated with polyethylene or other anti-corrosive material.

Suitable electrical leads (not shown) may be provided -to supply electrical energy to drive the motor 24 which 'leads pass from the sealed conduit box 73 mounted on top of the fan housing 12 through the conduit tube75 to malte `electrical connection with the motor 24.

Motor 24 is conventionally provided with cooling air inlets 74 and 76 at its opposite ends. The motor is further conventionally provided with one or more internal blower wheels for cooling the motor windings and the hot air exiting from the motor passes outwardly through a plurality The unit is provided with a pair of air outlet conduits 86 and 88 passing upwardly through the fan housing 12 through which the hot air from the motor passes outwardly from the unit. Bale 82 is provided with a pair of arcuate shaped end portions 90 and 92 and a pair of nat radial side plates 94 and 96 which Iact to seal off the chamber 84 by tightly engaging the outer surface of the 'motor 24 and the interior of motor housing 22.

The direction of contaminated air or gas flow through the fan housing is from left to right in FIGURES 1 and 2. The dashed line arrows in FIGURE 1 indicate the path of cooling air flow through the motor 22. The cooling air is drawn from outside the duct system to which the fan is connected and enters through pipe 52. This rela'- tively cool ambient air is drawn into the inlet tube 52 by the action of the centrifugal blower 44 mounted on a rearwardly extending shaft 42. Barrier plate 46 is provided with inlet hole 48 of (proper size for the particular blower wheel 44 so that the `pressure build-up on the discharge side of the blower does not recirculate into the inlet of the blower. All the air passing through the blower wheel is now at a higher pressure than the atmosphere and does two things. It ilows directly into the motor Ventilating inlet 74 nearest to the blower wheel and also passes over the outside surface of the motor with a relatively high veloctiy on its way to entering the air inlet 76 on the other side of the motor. At each inlet of the motor the pressure is now higher than it would 'normally be if the motor were operating in free air. This results in an increased air flow at the same time overcoming the resistance of the outlet tubes and any pressure loss that might result from the baffles and enclosure. An important yfeature lies in the action of the baffle 82 which separates this incoming cool air from the warm air exiting through outlets 78 and 80 in the motor and passing out through outlet conduits 86 and 88. In this way, the incoming cool air is never mixed with the exiting hot air which has taken up heat from the coils of the motor.

FIGURE shows a modified embodiment wherein the motor indicated at 24a is of slightly diferentV construction in that instead of having cooling air inlets at each end the motor is provided with circumferentially spaced inlets 79 similar to outlets 78 and 80. In this case the baille 92a is somewhat shorter in length so that it only encloses the motor outlets. Cooling air ow through the interior of motor 24a is from inlets 79 to outlets 78 and 80 in FIGURE 5.

Motors 24 and 24a may be of conventional construc tion and by way of example only one group usable with the present invention are those manufactured by the General Electric Company and listed as types 5KH33GG, 5KH35KG, and 5KH43MG. y

FIGURE 6 shows the vaneaxial fan 10 of the present invention connected in a conduit system comprising a large inlet conduit 98 for contaminated gas and a smaller outlet duct or conduit 100. Flange 14 of the vaneaxial Yfan 10 is connected to a similar flange 102 on inlet duct 98. Positioned between the vaneaxial fan and the 'outlet duct 100 is a transition duct 104. Cooling air is supplied to inlet conduit 52 by a liexible hose 108 leading to clean outside air. The inside diameter of hose 108 should be the same as or larger than the outside diameter of the inlet tube S2. The fan should be connected to a duct 100 of the same size as inlet duct 98 or if connected through transition element 104 the angle of the transition element should not be greater than 30 and preferably less.

It is apparent from the above that the present invention provides a novel vaneaxial fan particularly suited for use in conjunction with corrosive or other types of contaminated gases. The novel cooling arrangement for the enclosed motor makes it possible to utilize inexpensive and lightweight plastic materials. For example, the air flow fan blades may be made of polypropylene, the fan hub of a molded polyester, and the fan housing of polyethylene or polyvinylchloride. Similar plastic materials may be used for the other parts exposed to the corrosive iluid. The completely enclosed ball bearings require no lubrication and the manner of mounting the motor in the unit substantially reduces vibration.

The motor cooling feature of the present invention is quite important as evidenced by the fact that almost all motors are provided with an arrangement for venting and cooling the windings in order to prevent them from over heating. The degree of heating of the motor windings is usually the controlling factor as far as loading or over-loading a motor is concerned. For example, a motor designed to produce one-quarter horsepower with a temperature rise of 40 C. above an ambient temperature of 50 C. cannot be used on a quarter-horsepower load if the ambient temperature were 60 C. as the total temperature of the windings might then become 100 C. instead of the C. for which it was designed. Conversely, a quarter-horsepower motor with a 40 C. permissible temperature rise if used in a chilled atmosphere where the temperature could never exceed 30 C. could very easily take an overload which might cause its windings to rise to a temperature of 60 above ambient since this would again only bring the total temperature of the windings to 90 C. The temperature rise of the windings as distinguished from the total temperature of the windings is based upon eiciency of the cooling of the windings. This efficiency of cooling is, in general, directly related to the amount of air that can be caused to flow through the windings. For this reason, fans have been made in the past where drive motors were placed in enclosures and supplied with forcedair from an external source. However, insofar as is known, there has never been any provision for separating the air entering the inlet off the motor from the air discharged from the outlets of the motor. The result has always been that the entering cool air and discharged warm air became mixed and raised the ambient temperature so that the temperature of the air re. entering the motor inlet and being forced over the wind= ings has been at an elevated temperature caused by mixing of the warm air and cold air in the chamber in which the motor is located. This is to be clearly distinguished from the novel baffle arrangement of the present invention which completely separates the warm and the cold air by providing an adequate barrier that e11- closes the motor outlets and connects them to discharge tubes coupled to the outside of the unit.

The construction of blower 44 of the present invention is important in creating a positive pressure and insuring that warm air does not recirculate into the blower inlet. The air being discharged from the periphery of the centrifugal blower creates a pressure within the motor housing 22 or 22a which not only overcomes the resistance of the tubes and impediments to internal air ow, but augments the pressure developed by the conventional internal motor blower wheels causing more than the normal amount of cooling air to ilow through the motor, thus helping reduce the motor winding temperature. A further advantage is that air is caused to flow at relatively high velocity over the outside shell of the motor 22 on its way to the inlet at the opposite end of the motor from :the blower wheel 44. The whipping action of the air as it passes over the surface of the motor has a considerable cooling effect which further reduces the temperature rise of the motor permitting additional loading.

In order to insure air tightness of the motor chamber, seal 36 is provided surrounding the motor shaft. The eiectiveness of this seal is largely determined by the pressure differential between the fan chamber and the motor chamber. Since the blower 44 within the motor housing or chamber creates a positive pressure within the motor housing it virtually balances the pressure on the opposite side or in some instances may exceed it so that inward flow around the seal cannot take place.

As a result of the novel construtcion of the present invention, the fan can be made of streamlined, compact, light, eiiicient, and low-cost material. The substantial reduction in temperature of the motor makes it possible to utilize plastic materials which might otherwise be damaged by increased operating motor temperatures. Furthermore, the axial flow fan of the present invention makes possible the use of e'icient guide vanes between the fan enclosure and the motor housing to convert the rotational effect of air from the fan into usable pressure, thus making the device of the present invention a relatively high volume fan capable of producing maintained air flow at relatively high pressures such' as sometimes result from its use with duct work and other Ventilating devices.

The invention may be embodied in other speciiic forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States Letters Patent is:

1. An air moving device comprising a cylindrical fan housing, a fan mounted in said housing, a motor in said housing, direct drive means coupling said motor to said fan, a sealed chamber surrounding said motor, baffle sealing means dividing said chamber into two compartments, said motor having a cooling air inlet communicating with one of said compartments and a cooling air outlet communicating with the other of said compartments, means for supplying cooling air under pressure from outside said fan housing to said one compartment, and means coupling said other compartment to the exterior of said fan housing.

2. A device according to claim 1 including a cooling air inlet conduit communicating with said chamber and passing out of said fan housing, and means connected to said inlet conduit for supplying cooling air from a location remote from the exterior of said fan housing.

3. An air moving device comprising a cylindrical fan housing having open inlet and outlet ends, a fan mounted in said housing adjacent one of said ends, a motor mounted coaxially within said housing, an output shaft at one end of said motor driving said fan, said motor having cooling air inlets at each end and cooling air outlets intermediate said ends, a sealed chamber surrounding said motor, means for introducing cooling air under pressure into said chamber adjacent the other end of said motor, baflle sealing means for isolating a portion of said chamber surrounding said motor outlets from the remainder of said chamber, and means coupling said chamber portion to the exterior of said fan housing.

4. A device according to claim 3 including a plurality of radial, axially extending vanes surrounding said chamber.

5. An air moving device comprising a cylindrical fan housing having open inlet and outlet ends, a fan mounted in said housing adjacent one of said ends, a motor and impeller mounted coaxially within said housing, a irst output shaft at one end of said motor driving said fan, a second output shaft at the other end of said motor driving said impeller, said motor having cooling air inlets and cooling air outlets, a sealed chamber surrounding said motor and impeller, an inlet conduit passing through said fan housing and communicating with said chamber adjacent said impeller whereby said impeller draws air from outside said fan housing into said chamber, baffle sealing means engaging the interior of said chamber and the surface of said motor for isolating a portion of said chamber surrounding said motor outlets from the remainder of said chamber, and conduit means coupling said chamber portion to the exterior of said fan housing.

6. A device according to claim 5 wherein said impeller comprises a blower wheel.

7. A device according to claim 6 wherein said motor is provided with air inlets at each end and air outlets intermediate said ends.

8. A device according to claim 6 wherein said motor is provided with both air inlets and air outlets spaced over its surface intermediate its ends.

9. An air moving device comprising a cylindrical fan housing having open inlet and outlet ends, a fan mounted in said housing adjacent one of said ends, a motor and blower wheel mounted within said housing on the axis of rotation of said fan, said motor having air inlets and outlets, a iirst output shaft at one end of said motor driving said fan, a second output shaft at the other end of said motor driving said blower wheel, a sealed cylindrical chamber surrounding said motor and blower wheel, an inlet conduit passing through said fan housing and communicating with the end of said chamber adjacent said blower wheel, a barrier plate in said chamber between said inlet conduit and said blower wheel having a central aperture centered on the axis of rotation of said fan, baffle sealing means engaging the interior of said chamber and the surface of said motor for isolating a portion of said chamber surrounding said motor air outlets from the remainder of said chamber, and conduit means coupling said chamber portion to the exterior of said fan housing.

10. A device according to claim 9 wherein said sealed chamber is supported in said housing by a plurality of radial, axially extending vanes.

11. A device according to claim 10 wherein said fan housing, fan, vanes and chamber are all made of plastic.

12. A vaneaxial fan assembly comprising a cylindrical fan housing of plastic material having open inlet and outlet ends, a fan of plastic material mounted in said housing adjacent said inlet end, a motor and blower wheel mounted within said housing on the axis of rotation of said fan, said motor having air inlets and outlets, a rst output shaft at one end of said motor driving said fan, a second output shaft at the other end of said motor driving said blower wheel, a sealed cylindrical plastic chamber surrounding said motor and blower wheel, a

plurality of radial, axially extending plastic vanes secured to said housing and supporting said chamber within said fan housing, an inlet conduit passing through said fan housing and communicating with the end of said chamber adjacent said blower wheel, a barrier plate in said chamber between said inlet conduit and said blower wheel having a central aperture centered on the axis of rotation of said fan, baille sealing means engaging the 'interior of said chamber and said motor separating a portion of "said jchamber surrounding said motor air outlets from lsaid blower wheel and the remainder of said chamber, con- Vsaid fan housing.

References Cited by the Examiner UNITED STATES PATENTS 1,932,231 10/1933 Schmidt n 230-'117 5 2,397,171 3/1946 Troller et al. 230--117 2,726,807 12/ 1955 Lewis 230-117 X 2,793,506 5/1957 Moody 230-117 X FOREIGN PATENTS 10 1,025,557 3/1958 Germany. 1,038,706 9/1958 Germany.

DONLEY J. STOCKING, Primary Examiner.

15 ROBERT M. WALKER, LAURENCE V. EFNER,

Examiners. 

1. AN AIR MOVING DEVICE COMPRISING A CYLINDRICAL FAN HOUSING, A FAN MOUNTED IN SAID HOUSING, A MOTOR IN SAID HOUSING, A DIRECT DRIVE MEANS COUPLING SAID MOTOR TO SAID FAN, A SEALED CHAMBER SURROUDING SAID MOTOR, BAFFLE SEALING MEANS DIVIDING SAID CHAMBER INTO TWO COMPARTMENTS, SAID MOTOR HAVING A COOLING AIR INLET COMMUNICATING WITH ONE OF SAID COMPARTMENTS AND A COOLING AIR OUTLET COMMUNICATING WITH OTHER OF SAID COMPARTMENTS, MEANS FOR SUPPLYING COOLING AIR UNDER PRESSURE FROM OUTSIDE SAID FAN HOUSING TO SAID ONE COMPARTMENT, AND MEANS COUPLING SAID OTHER COMPARTMENT TO TEH EXTERIOR OF SAID FAN HOUSING. 